<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        .parent{
            width: 100%;
            height: 500px;
            background-color: #0a929a;
            margin-top: 100px;
            /* overflow: hidden; */
            /* position: absolute; */
            float: left;
        }
        .child{
            height: 200px;
            background-color: #aa04ba;
            margin-top: 50px;
        }
    </style>
</head>
<body>
    <div class="parent">
        <div class="child"></div>
    </div>
</body>
</html>